STOMACH CANCER
IMMUNOTHERAPY
A complete guide to immunotherapy in gastric and gastroesophageal junction cancer โ how checkpoint inhibitors work, who benefits, which agents are available, and how to access immunotherapy at specialist centres in China.
analyticsAt a Glance
- check_circleNivolumab + chemotherapy is now standard first-line therapy for PD-L1 CPS โฅ5 advanced gastric cancer
- check_circleMSI-H gastric cancer responds exceptionally well to PD-1 inhibitors โ often as first-line monotherapy
- check_circleChinese PD-1 inhibitors (sintilimab, camrelizumab) are NMPA-approved at substantially lower cost
- check_circleCancerFax coordinates access to immunotherapy at specialist gastric cancer centres in China
How Immunotherapy Works in Gastric Cancer
Gastric cancer was once considered poorly immunogenic โ an assumption overturned by the discovery that many gastric tumours express PD-L1 and that MSI-H gastric cancers respond remarkably to checkpoint inhibition. PD-1/PD-L1 inhibitors now form an integral part of first-line gastric cancer treatment for biomarker-selected patients.
โThe CheckMate-649 trial changed first-line gastric cancer treatment permanently โ adding nivolumab to chemotherapy became standard for the majority of patients with CPS โฅ5 disease.โ
How PD-1/PD-L1 Inhibitors Work in Gastric Cancer
Gastric tumours express PD-L1 on tumour cells and infiltrating immune cells, binding to PD-1 on T cells to suppress anti-tumour immune activity. PD-1/PD-L1 inhibitors block this interaction โ restoring the ability of existing T cells to recognise and destroy gastric cancer cells.
Why MSI-H Gastric Cancer Responds Better
MSI-H (microsatellite instability-high) gastric cancers accumulate thousands of mutations due to deficient DNA mismatch repair โ producing abundant neoantigens that attract dense T-cell infiltration. This immune-hot tumour microenvironment is exquisitely sensitive to PD-1 inhibitor therapy.
Key Immunotherapy Trial Results in Gastric Cancer
Landmark trial data establishing the role of checkpoint inhibitors in first-line and second-line gastric cancer treatment โ the evidence base that has shifted practice globally.
CheckMate-649: Nivolumab + Chemo vs Chemo (PD-L1 CPS โฅ5)
N=1581. Nivolumab + XELOX/FOLFOX vs chemotherapy alone in previously untreated advanced gastric/GEJ/oesophageal adenocarcinoma. Source: Janjigian et al., NEJM 2021.
- Median OS: nivolumab + chemo (CPS โฅ5)14.4 months
- Median OS: chemo alone (CPS โฅ5)11.1 months
- HR for OS (CPS โฅ5)0.71 (p<0.001)
ORIENT-16: Sintilimab + Chemo vs Chemo (All-comers, China)
N=650. Sintilimab + XELOX vs XELOX alone in first-line advanced gastric/GEJ cancer. Source: Xu et al., JAMA 2021.
- Median OS: sintilimab + XELOX15.2 months
- Median OS: XELOX alone12.3 months
Pembrolizumab in MSI-H Gastric Cancer (KEYNOTE-158)
Pembrolizumab monotherapy in previously treated MSI-H solid tumours including gastric cancer. ORR and durable responses demonstrated. Source: Marabelle et al., Lancet Oncol 2020.
- ORR (pembrolizumab, MSI-H gastric cancer)~45โ57%
- ORR (pembrolizumab, MSS gastric cancer)<10%
Immunotherapy Agents Available for Gastric Cancer in China
A structured overview of PD-1/PD-L1 inhibitors and related immunotherapy agents used in gastric cancer treatment โ including Chinese domestic agents with NMPA approval.
| Agent | Target | Line / Setting | Biomarker Requirement | Regulatory Status (China) |
|---|---|---|---|---|
| Nivolumab (Opdivo) | PD-1 | 1st line + chemo | PD-L1 CPS โฅ5 (approved); all-comers benefit in CPS โฅ1 | NMPA approved |
| Pembrolizumab (Keytruda) | PD-1 | 1st line MSI-H; 2nd line+ | MSI-H or PD-L1 CPS โฅ10 (1st line); pan-tumour MSI-H | NMPA approved |
| Sintilimab (Tyvyt) | PD-1 | 1st line + chemo | All-comers (ORIENT-16) | NMPA approved |
| Camrelizumab (Airuika) | PD-1 | 1st/2nd line + chemo | PD-L1 positive tumours | NMPA approved |
| Tislelizumab (Baiji BGB-A317) | PD-1 | 2nd line+ | Unselected | NMPA approved |
| Nivolumab + ipilimumab | PD-1 + CTLA-4 | 1st line MSI-H | MSI-H | Available at major centres |
| Atezolizumab | PD-L1 | Combination trials | Trial-specific | Clinical trial access |
PD-L1 CPS vs MSI Status โ Two Different Predictors
Understanding the difference between PD-L1 CPS scoring and MSI status is essential for interpreting your immunotherapy eligibility results correctly.
PD-L1 CPS Scoring
- What CPS measuresCombined Positive Score (CPS) counts PD-L1-stained tumour cells and immune cells as a proportion of total tumour cells. CPS โฅ5 is the threshold for nivolumab benefit in CheckMate-649.
- CPS โฅ5 is commonApproximately 60โ65% of advanced gastric cancers have PD-L1 CPS โฅ5 โ meaning the majority of first-line patients are eligible for nivolumab addition.
- Predicts magnitude of benefitHigher CPS correlates with greater nivolumab benefit โ CPS โฅ10 and CPS โฅ20 patients derive progressively larger OS improvements.
- Does NOT require MSI-HCPS โฅ5 eligibility for nivolumab is independent of MSI status โ MSS patients with CPS โฅ5 still derive meaningful OS benefit from nivolumab + chemo.
MSI / MMR Status
- What MSI status measuresMicrosatellite instability-high (MSI-H) or mismatch repair deficiency (dMMR) reflects a high tumour mutation burden due to impaired DNA repair โ generating abundant immunogenic neoantigens.
- MSI-H is uncommon in gastric cancer (~5โ10%)MSI-H gastric cancers are a minority but derive exceptional benefit โ response rates to pembrolizumab monotherapy exceed 45% in MSI-H gastric cancer.
- May warrant IO monotherapy in 1st lineMSI-H gastric cancer patients may receive pembrolizumab or nivolumab without chemotherapy in selected cases โ particularly elderly or frail patients.
- Influences prognosis regardless of treatmentMSI-H gastric cancers have a better prognosis than MSS even before immunotherapy โ reflecting a more immune-active tumour biology.
Stomach Cancer Immunotherapy โ Key Numbers
The most important quantitative benchmarks from landmark immunotherapy trials in gastric cancer.
- HR 0.71OS hazard ratio: nivolumab + chemo vs chemo alone (CPS โฅ5, CheckMate-649)A ~29% reduction in mortality risk with the addition of nivolumab โ the trial result that established checkpoint inhibitor combination as first-line standard.
- ~45โ57%ORR with pembrolizumab in MSI-H gastric cancerExceptional response rates in a small but critically important biomarker-selected population โ among the highest IO response rates in solid tumours.
- ~60โ65%Proportion of advanced gastric cancers with PD-L1 CPS โฅ5The majority of advanced gastric cancer patients are potentially eligible for nivolumab addition in first-line treatment.
More from the Gastric Cancer Resource Library
Continue exploring gastric cancer treatment โ from HER2-targeted therapy and CLDN18.2 agents to advanced treatment access in China.
Frequently Asked Questions: Stomach Cancer Immunotherapy
My PD-L1 CPS is 3. Does that mean I cannot receive immunotherapy?
A CPS of 3 falls below the CPS โฅ5 threshold for nivolumab approval in the CheckMate-649 indication. However, this does not necessarily mean immunotherapy is excluded โ some Chinese domestic PD-1 inhibitors (sintilimab in ORIENT-16) demonstrated OS benefit in an all-comers population regardless of CPS. Additionally, if you are MSI-H, pembrolizumab eligibility is based on MSI status, not PD-L1 CPS. CancerFax can assess your full biomarker profile and identify the most appropriate immunotherapy option for your specific results.
What is the difference between nivolumab and sintilimab for gastric cancer?
Both are PD-1 inhibitors that block the PD-1/PD-L1 interaction and have demonstrated OS benefit in first-line advanced gastric cancer when combined with chemotherapy. The key practical differences are: nivolumab (Opdivo) is the originator molecule approved by FDA, EMA, and NMPA; sintilimab (Tyvyt) is a Chinese domestic PD-1 inhibitor approved by NMPA only, at significantly lower cost. Clinical outcomes in Chinese trials (ORIENT-16 vs CheckMate-649) are comparable. For international patients treated in China and continuing treatment at home, using sintilimab in China may create challenges obtaining equivalent therapy through the home health system โ CancerFax advises on this consideration as part of treatment planning.
Can immunotherapy be used after surgery for gastric cancer (adjuvant)?
The role of adjuvant PD-1 inhibition in resected gastric cancer is an area of active investigation. The ATTRACTION-5 trial (nivolumab adjuvant) did not show significant benefit in an unselected Asian population. However, the MATTERHORN trial (durvalumab + FLOT perioperative) and KEYNOTE-585 are evaluating perioperative IO integration. For MSI-H patients specifically, post-resection pembrolizumab is being studied. As of mid-2025, adjuvant immunotherapy is not standard of care outside a clinical trial for gastric cancer โ but relevant trials are accessible at Chinese centres via CancerFax.
How CancerFax Helps
CancerFax is a specialist cancer access and patient-navigation platform. We help patients and families understand their options, organise medical records, coordinate hospital communication, and support cross-border treatment planning where appropriate.
We help collect and organise reports, scans, pathology, biomarker results, and treatment history for structured case review.
We communicate with hospitals or trial teams to assess whether a case may be suitable for further screening.
We support appointment coordination, document submission, translation, and direct communication with international departments.
For international patients, we help with practical coordination โ travel planning, hospital admission guidance, and local support.
If this option is not suitable, we help explore other relevant treatments, clinical trials, or advanced care pathways.
From inquiry through to follow-up, our coordinators provide a single point of contact for the family.
CancerFax does not guarantee treatment access, eligibility, or clinical outcome. Our role is to help patients access accurate information, structured review, and appropriate specialist pathways.
Has Your Gastric Cancer Been Tested for PD-L1 and MSI Status?
CancerFax reviews your biomarker results and treatment history to identify whether you are a candidate for immunotherapy โ and which PD-1 inhibitor or combination approach is most evidence-supported for your specific case.
This content is for informational purposes only and does not constitute medical advice. Always consult a qualified oncologist before making treatment decisions.